A common complaint of listeners with hearing loss is understanding speech in the presence of background noise. In most listening situations, the "noise" that masks a target talker is other voices. Realistic environments often have adverse listening conditions, such as reverberation and multiple sound sources. There are conflicting results reported in previous literature as to whether adults should use one or two hearing aids to best understand speech in noisy listening situations and it has been suggested that binaural interference increases with age. The goal of the proposed research is to determine whether removing one hearing aid helps or hinders speech understanding in complex listening situations. Auditory perceptual experiments will be conducted in younger and older adult listeners with sensorineural hearing loss to address three specific aims. First, to compare unilateral to bilateral amplification in multitalker listening environments. Second, to examine the effect of age on perceptual segregation of speech under conditions of informational masking. Third, to assess the effect of reverberation on aided speech understanding with multiple, simultaneous talkers. Overall, the results will be useful to audiologists and their patients. [unreadable] [unreadable] [unreadable]